Sketch catalog: "SV" numbers:

Lists sketches by city, gives each a number and limited bibliographic information,
and has an index by Opus, WoO, and Hess numbers, and a list of sketches for incomplete
works. The list is unfortunately incomplete and inaccurate; some corrections may be
made by consulting no. 4a.

For other major studies of Beethoven sketches, search in the Beethoven Gateway in the Category index (search term: sketch studies). Additional books and articles
that discuss Beethoven's sketches may be identified by searching "compositional process"
in the subject indexes.